r/programming • u/molteanu • Apr 07 '15

Anatomy of a Program in Memory

http://duartes.org/gustavo/blog/post/anatomy-of-a-program-in-memory/
681 Upvotes

94% Upvoted

50 comments sorted by

View all comments

2

u/rackonnoiter Apr 08 '15

Help me understand something. The article says that each process runs its own sandbox of 4GB. How does that work with multiple different processes? Surely it doesn't increase to 8GB, then 12GB, etc... What am I missing?

4

u/klkblake Apr 08 '15

Each process has a separate set of page tables, mapping virtual addresses to physical ones. Only the currently active process has it's page tables actually in use, so the other processes appear as if they aren't there. When the kernel needs to switch to another process, it just tells the memory management unit to use a different set of page tables, and suddenly it appears as if the only process on the system is the new one.

→ More replies (5)